PAR38 PAR Plots Options

[evilc66]

Time for a little more info for you on the PAR38's. This is the PAR plots for all the lens options we offer at 3 heights; 14", 20", and 30" from the top of the sensor to the bottom of the lamp.

Measurements were taken using an Apogee QMSW-SS Quantum meter on the daylight setting. Grid is made from a 27x27 square eggcrate and was measured on every other square. Eggcrate is on a 5/8" grid, so each measurement is spaced 1.25" apart. The grid was repositioned on each measurement group by finding the hotspot of the lamp using the PAR meter.

I only used the 12K for measurements, as the 20K is the same PAR.

I only measured a quarter of the spread, as it seemed a little redundant basically being duplicated 3 more times.

On to the fun part


14", 40 degree


20", 40 degree


30", 40 degree


14", 60 degree


20", 60 degree


30", 60 degree


14", 80 degree


20", 80 degree


30", 80 degree

Now, these numbers are taken in open air, so expect to see about a 10-20% increase in PAR from focusing of surface agitation and internal tank reflection.

[beeker]

When you take pics of your 40br can you post a PAR plot of the 4 bulbs running?

Like a front shot of your tank with the PAR ratings on the glass and sandbed? i might be getting a 200g marineland DD tank and want to make sure i can get a good amount of PAR on the sand since the tank is about 27 inches tall and not sure if i should go with 3 bulbs with 40 optics or 3 bulbs with 60 optics for spread and coverage

[evilc66]

What are the rest of the tank dimensions?

[beeker]

Dimensions are 48*36*27

[evilc66]

Looks like you have already figured out what you need in my 40B thread. PAR with the 40 degree optics will be great for most any softie or lps. When you consider that you are hitting 250+ PAR just 10" up from the sand, it will be great for sps.

[CrazeUK]

At the risk of looking and sounding extermly dim..
I just built a LED light unit for a fluval edge, i worked out from all the bulbs i am getting about 1045 lumens.

Now how do i work out par?

[Mustang Boy]

as far as i know there is no conversion from lumens to PAR you will have to get or borrow a PAR meter to test the PAR output at different levels in the tank

[CrazeUK]

as far as i know there is no conversion from lumens to PAR you will have to get or borrow a PAR meter to test the PAR output at different levels in the tank

So which is more important?

[evilc66]

PAR. It's a much more accurate measurement of a lamps potential for growth. Technically PUR (Photosynthetic Usable Radiation) is the most accurate, as it weighs in only the wavelengths that are actaully used for photosynthesis of a certain type of chloropyll, and not for both types.

[CrazeUK]

PAR. It's a much more accurate measurement of a lamps potential for growth. Technically PUR (Photosynthetic Usable Radiation) is the most accurate, as it weighs in only the wavelengths that are actaully used for photosynthesis of a certain type of chloropyll, and not for both types.

Right so i need a par meter then :s

hope they not expensive!

[evilc66]

Well, they aren't cheap. The sensors can be bought for about $150, but you need a sensitive multimeter to use them (down to at least 3 decimal places), or the full meter itself is $350.

[kellerexpress]

sorry for the dumb question just trying to understand these numbers, how much PAR would some sps like acropora require? Just trying to get an idea if one bulb would be enough to cover my nano.

[evilc66]

Sps like 200 PAR or more to really thrive.

[alephnull]

Evil, I need a little help with this. I am sure it is simpler than I am making it out, but I am lost. When looking at the data, am I looking at where equal distances intersect to gauge what the par would be at that height?

Could you give me a few references to make it easier to tell what I am looking at? I really can't make heads or tails of the graphs. Thanks.

[evilc66]

The charts show PAR at a certain height and from a distance from center. If it's easier for you, just think of the chart as flat as opposed to peaked.

[alephnull]

The charts show PAR at a certain height and from a distance from center. If it's easier for you, just think of the chart as flat as opposed to peaked.

That makes it a bit more clear, thanks. So, at 20", 60 degrees, there is an approximately 4" diameter circle from 100par at the edge to 200par at the center. Is that about right? If so, is there an easy way to judge what the par increase will be as I travel higher in the tank?

Thanks again. =)

[evilc66]

It's almost 5", but you have the right idea. If you want an estimation on what you would get higher in the tank, just look at the 14" plot.

[alephnull]

It's almost 5", but you have the right idea. If you want an estimation on what you would get higher in the tank, just look at the 14" plot.

I need to learn how to be smarter. Thanks.

[kdino]

so am i looking at this correctly???? at 30iches with 60 degree optics there wil be about 100par on the sand...is this correct...and then it moves up accordingly 20" at 200 and 14" with about 350?

[evilc66]

Yes, but remember that those are peak values directly under the lamp. PAR drops as you move off center.